The present invention relates to a novel hydrocarbon oil based antifoam composition. Antifoams based on hydrocarbon oils, such as mineral oil, that contain dispersed hydrophobic solid particles are well known in the art. Although effective in easy-to-defoam solutions of high surface tension, their performance is much more variable in concentrated surfactant solutions particularly those containing ionic surfactants. This limitation arises, in part, from the intrinsically higher surface tension of hydrocarbon oils relative to other antifoam vehicles such as silicon oil. To overcome this problem, various compounds have been suggested to increase the rate or extent of spreading of the antifoam. These agents are generally low to intermediate hydrophilic-lyophilic balance (HLB) nonionic surfactants that are soluble or dispersible in hydrocarbon oil, such as disclosed in U.S. Pat. No. 3,076,768. However, their effect is often variable and their utility has been questioned, (see, for example, U.S. Pat. No. 3,207,698 and GB Pat. No. 1,166,877).
Because hydrocarbon oil, and particularly mineral oil, is a relatively inexpensive antifoam vehicle, it is desirable to develop a hydrocarbon oil based antifoam that is highly effective in difficult-to-defoam aqueous based surfactant or protein solutions.
It has now been found that certain clearly defined mixtures of specific hydrocarbonsilicone copolymers, organo-silicone surfactants and fillers such as silica are highly effective with hydrocarbon oil as antifoams for these difficult-to-defoam surfactant solutions. Furthermore, certain combinations have high antifoam performance in ionic foaming solutions while other are particularly suited to defoaming nonionic surfactant or protein based solutions.
The use of hydrophobic silica in hydrocarbon oil based antifoams is well known as disclosed in U.S. Pat. Nos. 3,076,768; 3,207,698; 3,388,073 and 3,714,068. U.S. Pat. Nos. 3,912,652 and 3,959,176 deal with the use of hydrophobic silica in polyoxyethylene and polyoxypropylene copolymers.
The use of hydrophilic silica that is activated, in situ, in a non-silicone oil based antifoam is disclosed in U.S. Pat. No. 3,304,266 for a water insoluble polyalkylene oxide and in G.B. Pat. No. 1,166,877 using an alkoxy silicone chloride as the hydrophobing agent.
The use of intrinsically hydrophobic fillers in organic liquids is well known. For example, Canadian Pat. No. 508,856 discloses N,N distearyl ethylene diamine in white spirits, while the use of finely divided polyolefin polymers or polyesters dispersed in organic liquids in disclosed in U.S. Pat. No. 3,705,859. A conventional organic surfactant is alleged to improve the performance of the latter composition. The use of fatty acid salts is disclosed in G.B. Pat. No. 1,267,482 while low molecular weight polyethylenes (500-25,000) in combination with mineral oil and conventional organic nonionic emulsifiers is disclosed in U.S. Pat. No. 3,909,445.
The use of surfactants to promote spreading and to improve the performance of hydrocarbon oil-silica antifoams is claimed in U.S. Pat. Nos. 3,076,768 and 3,408,306, but these surfactants are conventional organic surfactants or emulsifiers. The efficacy of such spreading agents is questioned in U.S. Pat. Nos. 3,207,698; and 3,714,068 and G.B. Pat. No. 1,166,877.
U.S. Pat. No. 3,691,091 describes the use of organo-silicone compounds to improve the performance of silicone oil-silica based antifoams. However, the organo-silicones are of a different type than that used in the present invention.
The use of silicone-glycol copolymers in association with silicone oil and silica is disclosed in various Dow Corning Patents: U.S. Pat. Nos. 3,746,653; 3,784,479 and 3,865,544. The concentrations claimed are 70-98.9 wt. %. The compositions of the present invention employ a hydrocarbon oil, such as mineral oil, as the vehicle and not a silicone oil.
None of the patents cited above mentions the use of hydrocarbon-silicone copolymers of the type disclosed herein, in combination with a hydrocarbon carrier oil and a hydrophobic filler. Nor do these patents describe the use of organo-silicone surfactants of the type found effective here, in hydrocarbon oil based antifoams.